1. Field
The present disclosure relates to light sources, and more particularly to light sources using optics to produce substantially spherical emission patterns.
2. Background
Solid state devices, such as light emitting diodes (LED)s, are attractive candidates for replacing conventional light sources such as incandescent, halogen and fluorescent lamps. LEDs have substantially higher light conversion efficiencies than incandescent and halogen lamps and longer lifetimes than all three of these types of conventional light sources. In addition, some types of LEDs now have higher conversion efficiencies than fluorescent light sources and still higher conversion efficiencies have been demonstrated in the laboratory. Finally, LEDs require lower voltages than fluorescent lamps and contain no mercury or other potentially dangerous materials, therefore, providing various safety and environmental benefits.
The typical LED has a lambertian emission pattern. This means that light emitted from the LED typically spans a hemispherical arc. This emission pattern may limit the use of LED light sources, or other solid state lighting devices, as replacements for conventional light sources for incandescent, halogen and fluorescent lamps, which emit light in all directions. An LED light source that is used in an incandescent light bulb, for example, may result in undesired dark spots in the downward direction. In common lighting applications, such as desk, floor, and table lamps, this can result in no downward light to enable work or reading tasks.
Accordingly, there is a need in the art for a solid state light source that has an emission pattern that better resembles conventional incandescent, halogen and fluorescent lamps.